2015-药物合成反应课件-第六章 氧化反应.pptVIP

第六章 氧化反应 Chapter 6-Oxidation Reaction Oxidating Reagent 1. Oxidation of Alkane Selective oxidation of saturated alkane is very difficult !!! 1. Oxidation of Alkane Reactivity: Primary Secondary Tertiary Benzylic Oxidation Cerium (IV) ammonium nitrate（CAN） Oxidation to alcohol/ester Benzylic Oxidation Oxidation to aldehyde Benzylic Oxidation Etard Complex Etard Complex: Chromyl chloride/alkane 2: 1 Oxidation to ketone Oxidation of Ketone Oxidation of Ketone Oxidation of Ketone Oxidation of Allylic Carbon Riley Oxidation Riley Oxidation Mechanism Riley Oxidation Applications Mehta, G., Shinde, H. M. Tetrahedron Lett. 2003, 44, 7049-7053. Fürstner, A., Gastner, T. Org. Lett. 2000, 2, 2467-2470. Allylic Oxidation Collins Reagent Double bond shift Allylic Oxidation VO(OR)Cl2 Oxidation of Alcohol 1. Oxidations of Primary and Secondary Alcohols Intermolecular Intramolecular Oxidation of Alcohol Oxidation of Alcohol Formation of carbonyl compounds Jones oxidation : Cheap, easy to carry outsuitable for robust substrates on a big scale. Neither suitable for very acid sensitive substrates, nor for the preparation of many aldehydes. Collins oxidation : Cheap, but under anhydrous conditions. Produce very good yields of aldehydes and ketones in uncomplicated substrates. PDC and PCC are more expensive reagents that normally guarantee the best results in difficult cases. Oxidation of Alcohol-Jones Jones Oxidation Jones Oxidation Waizumi, N., Itoh, T., Fukuyama, T. J. Am. Chem. Soc. 2000, 122, 7825-7826. Crimmins, M. T., Jung, D. K., Gray, J. L. J. Am. Chem. Soc. 1993, 115, 3146-3155. Oxidation with Mn Oxidation with Ag/Pb Oxidation with DMSO DMSO-DCC (Pfitznor-Moffatt) DCC is the most widely used activating agent that needs to be applied in excess (usually 3 equivalents or more) the oxidation only works with catalysts that are only moderately acidic compounds such as ortho-phosphoric acid (H3PO4), dichloroacetic acid and the pyridinium salts of strong acids Pfitznor-Moffatt